High Current-Gain Implantation-Free 4H-SiC Monolithic Darlington Transistor

An implantation-free 4H-SiC Darlington transistor with high current gain of 2900 (J_C = 970 A/cm² and V_CE = 6 V) at room temperature is reported. The device demonstrates a record maximum current gain of 640 at 200°C, offering an attractive solution for high-temperature applications. The monolithic Darlington device exhibits an open-base breakdown voltage of 1 kV that is less than the optimum bulk breakdown due to isolation trench between the driver and the output bipolar junction transistor. On the same wafer, a monolithic Darlington pair with a nonisolated base layer was also fabricated. At room temperature, this device shows a maximum current gain of 1000 and an open-base breakdown voltage of 2.8 kV, which is 75% of the parallel-plane breakdown voltage.